944 Leak at Injectors

[rwstrobe]

I just purchased an 86 944 NA that is generally in great condition. But, it does have a couple of fuel leaks bubbling up from where the injectors are seated on the manifold.

I have already done the following:
- Removed old O-rings and pintle "hats"
- Cleaned injectors with carb cleaner
- Replaced all o-rings, and pintle "hats" with genuine Porsche kits
- Cleaned the attachment points on the fuel rail and manifold
- Used ATF to lubricate the o-rings for installation
- Reinstalled

The injectors look fine, and I don't see any damage, cracks or gaps. The heads look fine too, but I noticed that the pintle seats would spin around on a couple of the injectors at least (didn't check all for spinning, noticed 1/2 way through, and couldn't tell on the first two with the new hats on). It is a pretty substantial leak, and enough that I won't drive it for fear of a fire.

The other thing is that it seems very difficult to get the fuel rail reattached and everything sealed well with the injectors on the rail first. So, I put the injectors in first and felt for that "snap" that gave them a snug fit. But, it seems very difficult to get the fuel rail to "snap" back on the injectors, so catch-22...

I'm trying to determine if this is a seal problem or a broken injector problem.

Please let me know what you think. Thanks!

[944tothefloor]

I'd say it's possible but unlikely that the injectors are leaking. I would suspect the fuel rail, as they are known to develop tiny cracks that you simply can't see. Vibration is a cause.

Gasoline is very sneaky, and tracking down its source of leak can be challenging; gas is highly volatile, meaning that it can seep through tiny spaces at high speed. This can make it exceedingly difficult to pin point where a leak is coming from.

This may be redundant, but look again to try to find the origin of the leak.
Take a close look at your rail. It shouldnt be a tough fit, but if it is, it might be because it got bent and therefore cracked.

[Volhv]

I had a leak coming from where the plastic of the injector met the metal part. What alerted my was a hissing sound after I parked my car and shut it off.
Replaced all 4 with with good ones from a early car. It's been running with no issues. The early injectors deliver a tiny bit more fuel, but it's not enough to matter.

[968 GUY]

Swap them around to see if the leak is coming from a specific injector. Check the sealing areas on the manifold for scratches.